5 friction/clutch clearance issue in a 904

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67CUDA273

67CUDA273

1967 Cuda RestoMod
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I'm trying to use 5 clutches/frictions in the front clutch assembly on my 904, and I'm running into a clearance issue. Before the wave snap ring goes in, a pressure plate must first go over the clutches/frictions. With the extra clutch/friction, I don't have enough clearance to install the snap ring. The pressure plate is too thick. Is there a modified pressure plate that I need? Can I just use an extra steel in place of the pressure plate? Thanks guys.
 
stock are .086....

use the .061 disc that are the same at the rear clutch disc...

and you should have .068 steels..
 
You don't need 5 frictions in the front, 4 is all. The direct, maybe if your running big HP and a trans brake. Every time I think about it, comes down to too much work for too little gain. It's all about line pressure and a good shifting valve body.
 
PoisonDart74 said:
You don't need 5 frictions in the front, 4 is all. The direct, maybe if your running big HP and a trans brake. Every time I think about it, comes down to too much work for too little gain. It's all about line pressure and a good shifting valve body.
Click to expand...
duh... the direct drum is the front one. and to the op, you are working with a 5 disc drum arent you?
 
zijmer said:
duh... the direct drum is the front one. and to the op, you are working with a 5 disc drum arent you?
Click to expand...

Yes the direct drum. It's the stock 904 4-disc drum. I didn't know if there was a way to modify the 4-disc drum to accept the 5 discs either by machining or a modified pressure plate. In all honesty my HP application is mild. A 273 bored .30 over with a mild setup.
 
Here's a shot of the direct drum with the new steels/frictions. You can see there's not enough room left for the pressure plate and the snap ring. Below is a pic of the new friction (red, on left) compared to what was on there (I'm assuming stock)
 

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You do know there are several different thickness snap rings, right?
 
sorry, you cant put five frictions in that drum. and you should be soaking the frictions in atf, not assembly lube.
 
ok..I call them front and rear...

front drum can hold 5 thins or 4 thick....

rear drum only hold 4 thins..
 
RustyRatRod said:
You do know there are several different thickness snap rings, right?
Click to expand...

I do, but the drum is packed right up to the snap ring groove without the pressure plate going on. It's roughly 3/16" thick. I think it's got to be machined or I need to scrap the 5 clutch/friction setup.

I'm curious to know how others that have made this upgrade have done so. Is it just using the 5 disc direct drum from the 999's? That might require a new pump as well because the drum is different. Thinking out loud..scratching my head..

Thanks all for the help so far!
 
if your not in a hurry to get this thing built there is a way to do it. the five disc drum, wider band and matching stator support was used behind the 360 in the cop cars in the late seventys. only for a few years they were non-lockup. so those stators are quite rare. but there are lots of drums and bands still availlible. so... if you know of a good machinist, you can cut the backside of your stator to fit the 360 drum. there is enough material there to do it. ( ive done it ). then with the wider front band you basicly have you 999 minus the gearset.
 
The trans lube you smeared on the clutch plates can take up a whole lot more space than you might think. You should be installing the discs and steels dry and checking the clearance with a feeler gauge and adjusting it accordingly with the selective snap ring that gives you the proper clearance. Personally I like to see .075-.080" with a 5 disc setup checked dry. Then you pull the discs back out and soak them in ATF and reassemble it.

It's possible you have one of the thickest selective snap rings. Combine that with the assy. lube and there's your zero clearance.
 
The thin frictions are roughly the same thickness as the steels. The friction in that pic look much thicker.

4 x .086 = .344
4 x .068 = .272
total .616

5x .061 = .305
5x .068 = .340
total .645

It's a .030 difference loading the drum. Never had to machine a 4 clutch drum to put 5 clutches in using the thin frictions. You must you both thin frictions and steels.

I don't let vasoline or assembly lube into the clutch pack itself. Lube up the sealing surfaces and wipe any excess away. Drop the in steels/frictions dry, measure/adjust clearance. After that, soak frictions and drop in with dry steels.
 
zijmer said:
if your not in a hurry to get this thing built there is a way to do it. the five disc drum, wider band and matching stator support was used behind the 360 in the cop cars in the late seventys. only for a few years they were non-lockup. so those stators are quite rare. but there are lots of drums and bands still availlible. so... if you know of a good machinist, you can cut the backside of your stator to fit the 360 drum. there is enough material there to do it. ( ive done it ). then with the wider front band you basicly have you 999 minus the gearset.
Click to expand...

Thank you zijmer. I'm not in a hurry at all, and I already have a wider Kevlar front band from my rebuild kit. I'm going to try to pull the clutches/frictions out, dry everything out, and see where I'm at before looking at machining the stator. I'm glad to know that there is a solution, and one that works! Thanks a lot.
 
fishy68 said:
The trans lube you smeared on the clutch plates can take up a whole lot more space than you might think. You should be installing the discs and steels dry and checking the clearance with a feeler gauge and adjusting it accordingly with the selective snap ring that gives you the proper clearance. Personally I like to see .075-.080" with a 5 disc setup checked dry. Then you pull the discs back out and soak them in ATF and reassemble it.

It's possible you have one of the thickest selective snap rings. Combine that with the assy. lube and there's your zero clearance.
Click to expand...

Thank you Fishy68. I'm going to dry everything off and recheck when I get home from work tonight. That'll help me figure out where I need to go (thinner material) or just stick with 4.
 
crackedback said:
The thin frictions are roughly the same thickness as the steels. The friction in that pic look much thicker.

4 x .086 = .344
4 x .068 = .272
total .616

5x .061 = .305
5x .068 = .340
total .645

It's a .030 difference loading the drum. Never had to machine a 4 clutch drum to put 5 clutches in using the thin frictions. You must you both thin frictions and steels.

I don't let vasoline or assembly lube into the clutch pack itself. Lube up the sealing surfaces and wipe any excess away. Drop the in steels/frictions dry, measure/adjust clearance. After that, soak frictions and drop in with dry steels.
Click to expand...

Thank you Crackbacked. I'm picking up a caliper tonight to see exactly what I've got (once I dry everything out). With it being as off as it is, it's got to be because the frictions and maybe the clutches are just too thick. We'll know more tonight!
 
I installed 5 discs in a 4 clutch drum in my 904. I had the pressure plate machined with a narrow groove so the snap ring could be installed with the proper clearance.
 
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